Hydraulic control apparatus for machine tools



0t. 27, 1942. R.A.SCHAFEYIR Em; ,2

HYDRAULIC CONTROL APPARATUS FOR MACHINE TOOLS Filed Aug. 24, 1939 8 Sma ts- Sheet '1 Oct. 27, 1942. sc R ETAL 2,299,851

HYDRAULIC CONTROL APPARATUS FOR MACHINE TOOLS Filed Au 2 1, 19:59 8 Sheets-Sheet 2 R. A. SCHAF'ER ET AL 2,299,851

HYDRAULIC CONTROL APPARATUS FOR MACHINE TOOLS Filed Aug. 24, 1959 8 Sheets-Sheet s Oct. 27,1942. M CHAFER my 2,299,851

HYDRAULIC CONTROL APPARATUS FOR MACHINE TOOLS Filed Aug. 24, 1939 a Sheets-Sheet 'r Zikz/ezdar d faierz'b 5215/4/ 2" Jean ,9

meme Oct. 27, 1942 HYDRAULIC CONTROL APPARATUS FOR TOOLS Robert A.

Ind.,

Schai'er and Ralph Roda], Richmond, asslgnors to National Automatic Tool I(iiimpany, Richmond, Ind., a corporation oi diana Application August 24-, 1939, Serial No. 291,656

11 Claims,

Our invention relates generally to machine tools, and more .particularly to improvements in hydrauliccontrol apparatus for such tools.

The underlying principles of the hydraulic control apparatus of our invention are applicable to a large variety of machine tools, for controlling the actuation of the tools toward and from the work, or conversely, controlling the movement of the work toward and away from the tools, or may be applied to control the movement of any other part of such machine tool. Inthis application, our'invention is, however, described as applied to I the control of a horizontal unitary machine tool for performing drilling, tapping, reaming, facing and similar perations.

In accordance with our invention, the rate of feed of the tools toward the workis determined by improved metering devices which control the rate at which the oil may flow' from the end of the cylinder (opposite the end to which the oil under pressure is supplied) to the drain or sump. By virtue of this arrangement, the possibility of the tool pulling into the work due to the torque pull at the cut is substantially eliminated since such pulling force is resisted by the restricted flow of oil from the non-pressure end of the cylinder to the sump.

It is thus an object of our invention to provide an improved hydraulic feeding apparatus for machine tools, whereby the disadvantageous effect of having the machine tool pull into the work is substantially eliminated.

A further object of our invention is to provide an improved hydraulic control apparatus for machine tools which is very compact and in which the necessity for a large number or pipe fittings and bends in the oil flow conduits is eliminated. A further object is to provide a hydraulic control apparatus for machine tools in which a part of the machine tool .is hydraulically actuated under the control of a directional valve which in turn may be controlled either by a hand operated pilot valve or by an automatically operated pilot valve, the pilot valves being of small dimensions and being capable of actuation by the application or small forces, thus eliminating the necessity of providing large powerful solenoids for the actuation of the controlvalve, and also eliminating the necessity for the use of. springs. As is well understood in the art, springs in continuous use in apparatus of this character are ,unuesirable because of the possibilityof theireventual failure dueto the fatigue characteristic. By providing readily fit into the design of the apparatus, and which are comparatively inexpensive, may be utilized, and the hazard of using springs avoided.

A further object is to provide a hydraulic control apparatus for machine tools having a, manually operable pilot valve for controlling the actuation of a part of the machine tool and having an automatically operated pilot valve, in which means are provided to lock the hand operated pilot control valve when the automatic pilot valve is eilective and which, when the hand pilot valve is eflective, positions the automatic pilot valve properly with respect to the position of the maeasily operable pilot valves, small solenoids which chine .tool part in its cycle, so that the hand pilot valve may be rendered ineffective at any time during thecycle, whereupon the automatic pilot valve will be in proper position to control the actuation of the machine tool part through its proper cycle of operation.

A further object is to provide an improved hydraulic control apparatus for machine tools in which both automatic and manual control are possible, the manual control being particularly useful when the machine is being set up or tools are being changed, and in which means are provided for rendering the manual control inoperable whenever the automatic control is rendered efiectively operable.

A further object is to provide an improved hydraulic control apparatus for machine tools in which both manual and automatic controls are provided, and in which means are provided to prevent rendering the automatic control operative unless the hand control is in neutral or stop position, so that the machine may be stopped at any time in its automatic cycle by shifting from automatic to hand control, and upon reverting to automatic control the machine may resume operation at the point in the cycle at which the hand operation was interrupted, since, during the time that the machine is being operated under hand control, the automatic control is actuated (although ineffectively) so as to be in the condition at any time to resume control at the proper point in the cycle of operation,

A further object is to provide an improved hydraulic control apparatus for machine tools in which a directional valve is employed. and in which the sequence of operations of said valve difiers from" the desired sequence of operations of the part controlled by the valve. It will be understood that in prior constructions it was common practice to have the directional control valve (which actually controlled the admission of oil to the actuating piston and cylinder of the part of the machine tool to be moved) move sequentially to positions which would cause the head of the machine tool to operate through the following cycle: From neutral position through rapid forward traverse, coarse feed, fine feed, stop. and reverse traverse. In this type of control it was necessary, to initiate a new cycle, to move the directional control valve past the reverse position. This passing over of the reverse position caused a. momentary reverse movement of the tool carrying head, which sometimes resulted in an abrupt Jar of the head with consequent noise and wear upon the parts.

In the construction of the present invention,

the directional valve moves from neutral or stop position through fine feed and coarse feed to rapid traverse forward, then successively to coarse feed forward, fine feed forward, passing over stop r eut al, ra id traverse reverse, and finall I o n r p y 20 hydraulic control apparatus therefor.

returning to neutral or stop position.

To reach the rapid traverse reverse position, the directional valve must pass over the neutral or stop position, and then be brought back to .the neutral position to stop the reverse traverse. Thus in initiating a new cycle, it is not necessary for the directional control valve to move through the reverse traverse position in order to reach the forward traverse position.

A further object is to provide an improved form of hydraulic pilot valve controlled apparatus.

A further object is to provide an improved bydraulic control apparatus for machine tools which is very compact in construction, composed of few moving parts, which is easily adjusted and regulated, and which may be inexpensively manufactured.

A further object is to provide an improved hydraulic control apparatus formed in a unitary assembly in which substantially all of the working parts are readily accessible from the outside of the unit without completely dismantling it, for inspection and service.

Other objects will appear from the following description, reference being had to the accompanying drawings, in which:

Figure 1 is a side eievational view of an exemplary machine tool embodying the hydraulic control of our invention;

Figure 2 is an elevational view of the hydraulic control panel;

Figure 3 is a transverse sectional view taken on the line 3-2 of Figure 2;

Figures 4, 5 and 6 are fragmentary sectional views taken on the line 4-4, H and 9-4, respectively, of Figure 3;

Figure 'l is a fragmentary sectional view of the throw-over valve, together with fragmentary portions of the directional valve. the throw-over valve being shown in position for control by the automatic pilot valve:

Figure 8 is a view similar to Figure 7, with the throw-over valve in position for control by the hand pilot valve;

Figure 9 is a vertical sectional view showing particularly the directional valve in the stop or neutral position, and taken on the line 9-9 of Fig. 3;

Figure 10 is a view similar to Figure 9, showing the directional valve in position for rapid forward traverse;

Figure 11 is similar to Figu e 9, with the directional valve in position for coarse feed;

a Figure 12 is a view similar to Figure 9, showing the directional valve in position for fine feed; 7

Figure 13 is a view similar to Figure 9, show.- ing the directional valve in position for rapid reverse traverse;

Figure 14 is a developed sectional view taken substantially on the line 14- of Figures 2 and 13, showing particularly the governor and the coarse and fine feed adjusting valves;

Figure 15 is a diagrammatic view showing the complete system and the circuits for the opera' 10 tion of the solenoids;

Figure 16 is a diagram showing the hydraulic circuits, illustrating particularly the, connections between the various valves.

General description It is believed that the necessary detailed description of our invention will be more readily understood if it is preceded by this brief general'description of the machine tool and the The housing includes a head 21, a hydraulic reservoir or sump S (Fig. 15), a pump P driven by a motor 28, which also drives the tools 3|. A hydraulic feed cylinder 29 is rigidly secured to so the housing 25 and has a piston 39 carried by a piston .rod 32 which is rigidly secured to a portion of the sub-base 28. The sub-base 26 is suitably secured to the machine base 34 which may be formed integrally with or may be secured to 35 a work supporting base 29 having a table 38 formed integrally with or secured thereto, a piece of work 49 upon which the drills ll are to operate is illustratedas being bolted to the table 38. The control unit 42 is mounted upon the side of the housing 25, the latter being hollow and forming a reservoir for oil, andcompr-ises a lever 44 which is suitably pivoted on a downwardly projecting portion of the housing 25 and the right-hand arm of which is adapted to contact seriatim with 45 dogs 45, 46 and 41, which are adiustably secured upon a support 49 which is rigidly secured to the sub-base 26. The dogs 45, 46 and 41 are of unequal elevations so that as the housing 25 moves with respect to the sub-base 26, the lever 44 will 50 be pivoted through an angle determined by the height of the tops of the dogs 45, 48 and 41.

The left-hand arm of the lever 44 is operatively connected with an arm 50 by a rod 52,.the

arm 50 being connected to the automatic pilot valve, as willhereinafter be described in detail.

A manually operable handle 64 is connected to the. hand pilot valve, and a handle 56 is connected to a throw-over valve and locking mechanism, by which the automatic pilot valve and the 0' hand pilot valve may be alternatively rendered ineflective, and by the operation of which the hand pilot valve may be locked in position when the automatic pilot valve is rendered effective to control the operation of the machine.

65 A panel 59 is secured to the work piece base 26 and carries four push buttons 59, 69, GI, and 62, which operate electric switches. Push button 59 operates to close a switch59a which resets the hydraulic control unit-to initiate a cycle 7 of the tool head while the push button 60 closes -a switch sou (Fig. 15) to close and thereby to initiate a rapid reverse traverse operation of the machine tool head. Push button 6| starts the w electric motor 28, while .push button 62 stops this 5 motor by the use of a suitable switch mechanism.

interpreted to mean From limit switch 64 which is secured to the housing and has a switch actuator 66 which is engageable with a dog 68 adjustably positioned upon a rail I secured to the sub-base 26. The limit switch 64 includes a contact arm 64a (Fig. which it will be noted, is connected in parallel with the switch 60a.

Referring now to the diagrammatic viewof Fig. 15, it will be noted that the pump P draws the power fluid, which will hereinafter be referred to as oil, from the sump S and delivers it under pressure to a T I2, one branch of which is connected to a pressure relief valve body I4 which may be constructed in any suitable manner, but

is illustrated as including a conical valve I6 having a loose valve stem 18 and a compression coil spring 80. surrounding the stem and holding the valve 16 against its seat. The degree of compression of the spring 80 is such that the valve opens only when the pressure in the T I2 exceeds a predetermined maximum value, in the orderof 650 pounds per square inch, the oil bypassed through the valve body 14 being returned to the sump 8 through a conduit 62.

The other arm of the 1' I2 is connected to a pressure maintaining valve body 84 having a spring pressed valve 86 similar'to that included in the valve body 14 except that it may open at a much lower pressure, namely a pressure in the order of 50 pounds per square inch. A conduit 90 is connected to the valve body 84 so as to be supplied with oil at the pressure at which it is maintained in the T. Generally speaking, the oil supplied through the conduit 98 is provided for the actuation of the cylinder and piston 29, while the oil supplied through the conduit 90 is utilized for the actuationof the valve mechanism. Under certain conditions (when the directional valve isin neutral position, Fig. '9) as will appear hereinafter, the pressure in the conduit 88 drops to atmospheric pressure, and the pressure retaining valve 86 isthus necessary to maintain sufficient pressure in the conduit 90 for the actuation of the directional valve and its pilot valves.

In the following detailed description of the invention, in order tofacilltate following the hydraulic circuits, all passageways,'conduits, ports,

and the like, which are in communication with each other at all times, so that irrespective of the phase of the operating cycle, oil could flow from one toanother, will be given the same ref-. erence character followed by decimals to distinguish individual parts. Thus, for example, when it is stated that oil under pressure flows into a conduit bearing a. certain reference character, it will be understood that oil in all parts bearing that reference character followed by a decimal fraction will likewise be under pressure.

Similarly, all passageways, etc., through which oil is at all times free to discharge to the sump will be followed by the letter S which should be which the oil may flow freely to the sump."

' Hand to automatic throw-over value shall control the operation of the dtrec onal valve consists of a throw-over. valve which is onerated by the handle 56, the handle being in-' tended as illustrative of any suitable means for shifting this valve between its two effective powhen in the position shown in Fig. 8 renders the automatic pilot valve inoperative.

As shown in Fig. 3, the handle 54 is connected to a hand'pilot valve I03, the hand pilot valve being surrounded by a follower sleeve valve I05 and having a portion I0I of increased diameter provided with a hole I09 to receive a locking pin III formed at the end of a rack II3 which is engageable with the pinion teeth 98 formed on the stubshaft 92. A spring pressed detent II4 (Fig. 2), engageable with notches formed in the rack Ill, is adapted to hold the rack in either of its extreme positions with the locking pin III in engagement with the hole I09 or free from engagement therewith. By virtue of this construction, when the throw-over lever 56 is shifted to its upper (Fig. 2) or automatic position, the hand pilot valve lever 54 is locked in position.

The throw-overvalve I02 cooperates with a ported sleeve II2 which is pressed into a bore 6 in'the panel 96 and has a plurality of ports. hereinafter to be described in detail, some of which may be interconnected by annular passageways IIB and I20 formed in the throw-overvalve I02. The throw-over valve has an axially drilled hole I22S extending from end to end thereof, to permit flow of oil wheneverthis valve is shifted, the end of the bore '6 being in communication with the sump through a passageway I23S.

"' Hand and automatic pilot valves through ducts 90.3 and 90.4, respectively. The

automatic pilot valve I04 is secured to the arm 50, a sprin Dressed detent I24 being engageable in notches formed in a plate I26 so as to hold the arm in the position to which it is moved by the dogs45, 46, 41.

The'handle, 54 has a similar detent I28 able with recesses formed In plate I 30.

The automatic pilot valve I04 has a follower sleeve valve I06, having a pinion IIO formed integrally therewith, the corresponding hand follower sleeve valve I05 having as'irnilar pinion H5 formed integrally therewith, the pinions I I 0 and H5 meshing with a pair of racks I 32 and l'3l formed on a directional valve I33, which will be described in further detail hereinafter, the present consideration. being that, the follower sleeve valves I05 and-I06 always move through corresponding angular distances by virtueof the fact that each is geared to the directional valve I 99.

The sleeve valve I05 has an annular port 90.5 which through ports 90.1 communicates with a chamber 90.9 formed by milling awayportions of the pilot valve I03. Chambers 90. and 90.I3 communicate with the chamber 90.9 through pairs of ducts 90.I5 and 90.", respectively, while chambers I35S and I3'IS are formed'in the pilot valve I03 and communicate with a drain duct In a similar manner, the automatic pilot valve I04 has a chamber 00.I which communicates with the drilled passageway 90.4 through ports 60.6, the chamber 90.I0 communicating with chambers 00.I2 and 00. through pairs of ducts 00.I6 and 6018, respectively. Chambers i368 and I365 formed in the valve I04 communicate with an axially drilled passageway I40S through ports i428 and I44S, respectively, as shown in Figs.

ported sleeve II2 of the throw-over valve I02.

From the groove 6.4 the oil may flow through the annular passageway II8 (when the throwover valve is in the automatic position, as shown in Fig. 7). to an annular groove I48 which,

' through a duct represented by the dot-dash line I46.I communicates with the right-hand end (Fig. 7) of directional valve cylinder I52, It will be noted from Fig. 8 that oil cannot escape from the passageway I462 when the throw-over valve I02 is shifted to the hand control position.

The follower sleeve I06 of the automatic pilot valve has an annular groove I54 which, as shown in Fig. 6, is in communication with a cross drilled duct I54.2, the duct I542 leading to an annular.

passageway I54.4 formed in thethrow-over valve sleeve II2, the annulus I54.4 ,being connected with a similar annular groove I56 and a suitable passageway represented by the dot-dash line I56.I with'the left-hand end of directional valve cylinder I52.

In a similar way, the chambers I35S and I3IS communicate with the axially drilled hole I39S of the hand pilot valve I03, and the hand pilot sleeve valve I05 has an annular passageway I45 which communicates with a passageway I45.I leading to an annular passageway I45.2 formed in the sleeve II2 of the throw-over valve I02. An annulus I55 formed in the manual pilot valve sleeve I05 communicates with an annulus I55.I in the throw-over valve sleeve I I2 through a cross drilled hole I55.2. Thus, when the throw-over valve is shifted to the hand position, as shown in Fig, 8, the annulus I55.I communicates through the annular passageway on the throwover valve I02 with the annulus I46, the latter being in communication with the right hand end of directional valve cylinder I52 through the duct I40.I.

Similarly, when the throw-over valve is in hand control position, as shown in Fig. 8, the annulus I45 communicates, through cross drilled hole I45.I, annulus I45.2, annular passageway I20 of the throw-over valve, with annulus I56, and hence through conduit I56.I with the left-hand end of -the directional valve cylinder I52. It will be noted from Fig. 4 that the section of the automatic pilot valve I04 between chambers 00.I2 and I368 is a generally diamond shape, to form a slide valve with respect to port I46.I formed in the valve sleeve -'-I06. Similarly, the section of the pilot valve :IIIQbetween the chambers 00. and I368 is sucli'as to form a cut-oil valve for a port I54.I formed in the sleeve I06.. The sleeve I05 of the manual pilot valve I03 has ports corresponding with the ports I46.I and.

The automatic pilot valve I04 has a pinion I56 secured thereto (Fig. 3), the pinion having a pair of racks I60 and I62! (Fig. 2) in mesh therewith, these racks being operatively connected with the armatures or plungers of solenoids I64 and I66, respectively.

Disregarding for a moment the functions of the directional control valve I33, the hydraulic circuits by which this control valve may be shifted will now be described. It will be understood that the directional valve I33 (see e. g. Fig. 11) forms a freely sliding piston in its cylinder I52. The sole purpose of the pilot valves is to move the directional valve I33 rapidly to any one of its five positions, which are: (a) Stop, or neutral; (b) fine feed; (c) coarse feed; (d) rapid forward traverse; and (e) rapid reverse traverse. 7

These five positions of the directional valve are shown in Figs.-9, 12, 11, 10 and 13, respectively.

Assuming that the directional valve is in its.

stop or neutral position, and that the automatic pilot valve I04 is moved clockwise (Figs. 2 and 15) by the energization of solenoid I66 as a result of closing switch 56a. by means of the push button 50, the resulting operations 0! the pilot valve will take place substantially continuously, but will be described herein as if they took place in a series of separate steps. As soon as the pilot valve I04 starts to move clockwise, the ports I46.I and I54.I in the pilot valve sleeve I06 will be uncovered. As a result, 011 under pressure in the chamber 60. will flow through the port,

I54.I, annulus I54, cross drilled duct "4.2, to the annulus I54.4 oi the throw-over valve sleeve (and assuming that the throw-over valve I02 is in the automatic position of Fig. 7) through the annular passageway I20 oi the throw-over valve and hence to the annulus I56 of the throw-over valve sleeve and passageway I56.l to the lefthand end of the directional valve vylinder I52. At the same time, the oil from the right-hand end or the directional valve cylinder I52 flows through the conduit I43.I, through the annulus I46, annular passageway II6 otthe throw-over valve, annulus 6.4 of the throw-over valve.

sleeve, cross drilled duct I46.2,.annu1us I46 01 the pilot valve sleeve I06, port I46.I, and hence to chamber I36S. Oil under pressure is thus supplied to the left-hand end of the directional valve I33 and permitted to flow to the sump' from the right-hand end-thereot. The directional valve- I33 thus moves to the rightiFig. 'I) and by this movement through its rack I32 rotates pinion III clockwise.

Clockwise movement oi the pinion I I6 and consequent clockwise movement of the pilot sleeve I06 results in closure of the ports I46.I and. "H, thereby cutting oil. the supply of pressure to the left-hand end of the directional valve cylinder I52, and likewise cutting of! the connection to the sump from the right-hand end of the directional valve cylinder. Thus, any clockwise movement of the pilot valve I04 will immediatelyresuit in movement of the directional valve and consequent movement of the pilot valve sleeve.

I06 in a clockwise direction until the pilot valve I04 and sleeve I06 are in the same relative positions as these parts are shown in Figures 3 to 6, inclusive.

In a similar manner, rotation of the pilot valve I04 in a counter-clockwise direction results in a corresponding angular movement of the pilot valve sleeve I and leftward displacement of the directional valve I00.

The hydraulic circuits which cause the latter operation upon counter-clockwise movement of the pilot valve I04 will now be described. Oil under pressure supplied through the port 00.0 flows through chamberv90.l0 and passageways 90.I6 to chamber 90'.I2, through the now uncovered p'ort I46.I, annulus I46, cross drilled duct I461 to annulus 6.4 of the throw-over valve,

annular passageway IIO of the throw-over valve I02, annulus I40, duct I40.I to the right-hand end of directional valve cylinder I52, thus applying pressure to the directional valve causing its movement toward the left. The oil left-handend of the cylinder I52 flows outwardly through the duct I561, annulus I56 of the throwover valve sleeve, annular passageway I20 formed in the throw-over valve I02, annulus I54.4, duct I541, annulus I54, into the then uncovered port I54.I and chamber I008. As the result of the leftward movement of the directional valve I 03, the pilot valve sleeve I06 will be rotated counterclockwise, and thus follow the movement of the pilot valve I04 until the ports I46.I and I54.I are again closed by the pilot valve I04.

From the foregoing, it will be seen that when the pilot valve I04 is moved any angular distance in either direction, such movement is immediately followed by equal angular movement of front the the pilot valve sleeve I06 and proportional movement of the directional valve I03. In this way,

by the application of a relatively small torque to the pilot valve I04, relatively large forces may be hydraulically applied to the directional valve I33 for the shifting of the latter, and the control is such that the directional valve I33 follows substantially instantaneously, and in very accurate proportionality, the movement of the pilot valve.

The hydraulic circuits which are completed when the throw-over valve is in the hand control position, as illustrated in Fig. 8, will now be described. It will be noted from Fig. 8 that the throw-over valve I02 cuts oil communication from the ducts I461 and I541 which lead to the automatic pilot valve. In addition, it puts the duct I45.I in communication with the duct I56.I and puts the duct I551 in communication with the duct I40.I. 'It will be noted that the ducts I45.I and I551 correspond respectively with the ducts I461 and I541 of the automatic pilot valve. Thus, when the throw-over valve is in the hand position shown in Fig. 8, the hand pilot I00 and its sleeve I05 will operate in. the same manner as above described with reference to the pilot valve I04 and its sleeve I06, to control the shifting of the directional valve I00. Since. the operation of these parts'underhand control'corresponds exactly with their operation under the control of the automatic pilot .valv, it is believed that it is unnecessary to repeat the.details of the hydraulic circuits by which the shifting of the directional valve is accomplished under the control of the hand pilot valve I00 and its sleeve I05.

Coarse and fine jee d con'trola As previously stated, the rate at which the machine tool part is moved is determined by controlling the rate of flow of oil from the rod end of the actuating cylinder 29; The flow from this cylinder may be free for rapid forward traverse, may be, restricted by a coarse feed valve 7 'sleve I10, and thus permit for the coarse feed, or may be greatly restricted by the adjustable fine feed valve.

Thus, the rate at which the head is moved during the forward feeding portions of the cycle is determined by the rate at which oil may escape through a conduit I which is connected to the rod end oi. cylinder 29 (Fig. 15) and leads to a drilled passageway I60.I formed in the control panel 96 (Fig. 14'). The drilled passageway I60.I intersects the directional valve cylinder I52 and has a sidewardly directed branch I601 which communicates with an annulus I601 formed in a feed governor valve sleeve I10 which is held in place in the panel by an apertured plate I12. The valve sleeve I10 has a cylindrical bore I14 formed therein to receive the stem I16 of the governor valve, the stem I16 being formed integrally with a piston portion I10 which is guided in the bore I00 in which the sleeve I10 is fitted. The piston I10 and its stem I16 are ,pressed downwardly by a compression coil spring I02, the upper end of which is received in a socket formed in a removable plug I04 secured in the panel 96. The stem I 16 has an axially drilled hole I06S by which the space in the bore I 00 above the piston is "at all times, in free comnunication with the sump through the aperture I008 formed in the securing plate I12.

Stem formed therein to form passageways for oil around an annular valve seat I92 formed on the flow of oil from the annulus I601, ports 100.4 and chamber I085 through the slots I90 into a chamber I94 which is the part of the bore I00 between the piston I10 and the upper end of the slevee I10. It will be understood that the valve stem I10 is. normally in the position in which it is shown in Fig. 14, but that should the pressure within the chamber I94 become built up to a value sufficient to cause a piston I 10 to compress the spring I02, the piston I10 and the stem I16 willmove upwardly, thus partially closing the ports formed by the arcuate slots I90. These parts thus act as a governor to prevent the pressure within the chamber I04 from exceeding a predetermined value, such, for example, as 20 pounds per square inch.

The rate at which oil may escape from the chamber I04 determines the speed at which the cylinder 29 will move during the coarse feed and fine feed portions of the operating cycle. For the purpose of controlling the 'rate at which the oil may escape from this chamber I94 for the coarse feed portion of the cycle, an adjustable coarse feed valve I00 is provided. This valve is rotatable in a bore I90 and is non-rotatably secured to a control knob 200 which has a pointer on its base flange 202 for cooperation with graduations and indicia etched or otherwise marked upon a plate 204. The valve-I96 is held within its bore by a bushing 200 and has an arcuate V- shaped groove 200 of gradually tapering depth formed along a portion of its periphery for registration with a passageway I 04.I leading to the as the valve I is rotated, the cross sectional.

, area of that portion of the groove 200 which is adjacent the passageway I 94.I may be varied,

and since it is mainly that portion of the groove 200 of least cross sectional area which deter- I10 has a pair of arcuate slots I90 plied through a passageway mines the rate at which oil will flow from the passageway I 94.I to the drilled hole 2I0, the angular position of the valve I90 effectively determay flow freely from the drilled hole 2I0 of the valve I90.

In the coarse 'feed position of the directional valve I30, the oil flowing from the drilled hole 2 I may flow with a minimum of resistance'to the sump through a passageway 2l0.2 which communicates with a duct 2I0.0 and from the latter duct through the directional valve to the sump, as will appear hereinafter.

when the directional valve is in position for completing the fine feed portion of the machine cycle, the duct 2I0.0 is blocked, as will be described hereinafter, and the oil in the passageway 2I0.2 thus flows through the connecting passageway 2I0.4 to the fine feed adjusting valve 2I2 which is rotatable in a valve cylinder 2 formed in the panel 90.

Thevalve 2I'2 is of substantially the same construotion as the valve I90, although its V-shaped restriction groove 2l0 may be out less deep than the corresponding groove 200 of the valve I90.

The valve 2I2 has a control knob 2I0 secured thereto, this valve having a pointer cooperable with graduations and indicia formed upon a-plate 220 which is suitably secured to the panel 90, the valve beingheld in position by a bushing 222 threaded or otherwise suitably secured in the panel 90. The valve 2I2 has a port 2243 communicating with an axially drilled passageway 2258 which is in open communication with a passageway 2208 leading to the sump. It will be understood that the sump is located directly inside of ,the panel 90 so that any passageways, such as the passageway 2208, which extend to the inner surface of the panel 90, discharge into the sump. This is best shown in Figs. 2, 13, and 14, wherein the panel 90 is shown as secured over an opening 258 formed in the casing 25.

From the foregoing, it will be seen that when the passageway 2 I 0.3 is blocked by the directional valve, the oil from the rod end of the cylinder 20, after flowing through thegovernor valve I10, must flow successively through the fiow restricting valves I00 and 2I2, which constitute, respectively, the adjustable valves for coarse feed and fine feed.

The directional control valve The directional control valve I00, as previously described, is reciprocable in a cylinder I52, the head ends 220 and 200 forming in effect pistons for.reciprocation of the valve. The valve has annuiar passageways 202, 204 and 200 which are adapted to interconnect certain of the annular grooves formed in the cylinder I52.

Oil under pressure from the conduit 00 is sup- 00.I to an annulus 00.2. The previously described drilled passageway I0.I communicates with an annular groove I005 formed in the wall of the cylinder I52. Passageways 200s and 2408, communicating respectively with annular grooves .2098 and 24IS, discharge directly into the sump.

. mines the rate at which the oil may escape from the rod end of the cylinder 29-provided the oil trol valve commimicates with an annular groove 2I0.4 formed in the wall of the cylinder I02.

Operation of directional value As previously described, the position of the directional valve is quickly and accurately determined by the position of either the automatic pilot valve I04 or the position of the hand pilot valve I00, depending upon the position of the throw-over valve I02. The functions of the directional valve I03 will first be described with reference to Fig. 9, inwhich this valve is in its stop" or neutral" position. Under these circumstances, it will be noted that the oil under pressure supplied to the annular groove 00.2 flows freely, via the annular passageways 204 and 200 to the passageway 2408 to the sump. While both ends of the cylinder 29 are also in communication with the oil pressure supply, (via 00, 00.I, 00.2, 234. 242.2, 242.I, and 242, and via 00, "J, 80.2, 234, I003, I00.I, and I00) the pressure in the cylinder will be negligibly low; Thus even though the piston is of the usual diflerentiai type no motion of the cylinder and machine tool head will take place.

The advantage of having the oil under pressure connected substantially without restriction (the only restriction being that offered by valve 00) to the sump whenever the head is in neutral or stop position, is that the oil is not unnecessarily heated. If the oil from the pump were not thus substantially vented to the sump, the pump would have to force the oil past the high pressure relief valve 'I0,'with consequent undesirable heating of the oil and waste of power.

In the normal cycle of operations, upon energization of solenoid I00, the first movement of movement of the valve through these two feed positions has no noticeable effect upon the actuation of cylinder 29, the operation'of the directional valve during this portion of its cycle will nection with the operation of the fine feed conbe described as if this first movement of the directional valve and of the pilot valve took place slowly, as when I the throw-over valve is positioned for hand control, and the hand pilot valve is moved slowly through its successive positions.

It will be noted that when the directional valve I93 is in the fine feed position shown in Fig. 12, the oil under pressure supplied through the passageway 00.I flows through the annular groove 00.2 around the annular passageway 204 to the passageway 242.I and hence to the left-hand (Fig.

15) end of cylinder 29 tending to cause, the cylinder 29 to move to the left. At the same time, oil cannot be forced outwardly from. the right hand end of the cylinder 29 through conduit I00 to passageway I00.I and annular groove I00.0, be-

- cause the annular groove 100.0 is blocked by the directional valve. The oil, since, it cannot escape from the annular groove I00.0, must flow through the passageway I00.2 through the feed governor valve mechanism I10, I10, through the passageway I04.I and coarse feed control valve I00 to the passageway 2I0.2.

It will be noted from Fig. 12 that the passageway 2I0.3 is closed so that the oil cannot escape therethrough, leaving the passageway 2I0.4 and fine feed control valve 2I2 as the only avenue the rod end of the cylinder 29. By proper adjustment of the fine feed control valve 2I2, the rateat which the oil thus escapes from the rod end of the cylinder 29 to the sump may be accurately regulated to secure substantially any desired slow feed rate.

The second passing phase of the operating cycle of the directional valve, although of negligibly short duration, comprises its movement to coarse feed position, as shown in Fig. 11. In this figure. the supply of oil flows from the passageway 88.I to the forward end of the cylinder 29 through the conduit 242 etc., in the same manner as described with reference to Fig. 12. The flow ,of oil from the rod end of the cylinder 29 through the conduit IE8 is still prevented through the annular groove I883 by the directional valve, and therefore continues to flow as in the-fine feed posipassageway I94.I to the coarse feed control valve I96 and hence to the passageway 2I9.2. It will tion throughthe feed governor and through be noted from Fig. ,11 that the duct 2I0.3, which is in open communication with thepassageway 2IIl.2, is partially uncovered by the directional valve I 33 so that oil may flow from the annular groove 2I0.4 through the annular passageway 236 to the annular groove 24IS and hence through the vpassageway 2408 to the sump. Thus, the sole means for controlling the rate at which the cylinder 29 may move is the coarse feed control valve I96 with, of course, the intermediate control atiected by the feed governorvalve I18.

InFig. 10, the directional valve I33 is illustrated in the position it assumes to cause rapid 7 forward traverse of the head of the machine tool or rapid forward movement of the cylinder 29.

When in this position, it will be apparent from an inspection of Fig, 10, the oil under pressure supplied through the duct 8B.I flows through. the annular groove 88.2, annular passageway 234 to the annular groove 242.2, passageway 242.l and conduit 242, and hence to the forward end of the cylinder 29. The rod or right-hand. end of cylinder 29 is'vented to the sump through a hydraulic circuit 'including the conduit I68, passageway I68.I, annular groove I888, annular passageway 232 on the valve I33, annular groove 2395 and passageway238s.

It will be noted that in'Fig. 10 the directional valve I33 is at the right-hand end of its stroke. In the normal sequence of the cycle of opera tions, the rapid forward traverse, as; determined by the directional valve when; itisin the. position of Fig. 10 is followed by the coarsefeed forward operation when, the directional,valve is moved to the position in which it is shownin Fig. 11 to control hydraulic circuits previously described as effective to cause ,the coarse, feedingportion-of the operating cycle of the, machine.

Thereafter, the directional valve I33 is moved t .fineieedposition, as'shown in Fig. 12- and as above, described with reference to said figure.

Upon completion of the fine feeding portion'of the operating cycle, the solenoid I84 is.energized to move the pilot valve, and hence the directional valve, through stop or neutral position (shown in Fig, 9 and above described with reference thereto) to rapid reverse position.

For therapid reverse traverse, the directional valve ,I33,.is moved to its leftmost position, as

shown in Fig, 13. when in this position, the following hydraulic circuits are completed. I Oil under pressure supplied to the passageway 88.I flows through the connected annular groove 88.2

swinging the automatic pilot of the cylinder 29, thus applying pressure to the piston and cylinder tending to move the cylinder 29 to the right (Fig. 15). Oil from the forward end of cylinder 29 may escape to the sump through conduit 242, pasageway 24I.I, annular groove 242.2, annular passageway 238, around directional valve I33, annular groove 24IS and passageway 2408. It will be noted that the flow of oil into the rod end of cylinder 29 from the supply conduit 88 is unrestricted and similarly that the flow of oil from the forward end of cylinder 29 to the sump is likewise substantially unrestricted. As a result, the cylinder 29 and the machine tool head will move rapidly in a reverse direction.

After the completion of the rapid reverse traverse of the machine tool head, the directional valve will, of course, be returned to its neutral or stop position shown in Fig. 9.

Operation In the foregoing description of the various parts of the invention, the operation of these parts has been set forth in considerable detail, so that it -is believed that a brief general description of the operation of the machine as a whole, referring generally to Fig. 16, correlating the previous description of the various operations performed by the individual parts, will suflice.

Assuming that a work piece 40 has been secured in position upon the table 38 and that the tools 3| are such as require the cycle of feeding operations previously described, the operator will press push button BI to energize the electric motor 28, causing rotation of the tools II and the operation of the pump P to build up suitable operating pressures in the conduits 88 and 90. Thereafter, the operator will press push-button 59 to close switch 59a energizing solenoid I88 which moves the pilot valve I04 to rapid forward traverse position.

In order to get to rapid forward traverse poand 11, respectively. However, its movement from stop or neutral position to its rapid forward traverse position is continuous, and the only effect of the valve I33 passing through its line feed and coarse feed positions, is to decrease slightly the suddenness with which the oil under pressure is applied to the forward end of the cylinder 29, or

more exactly, the suddenness with whichthe oil pressure in the rod end of the cylinder 28 is relieved.

After the. head of the machine tool has thus been moved rapidly to the position at which the tools 3| are about to engage the work, the lower end of arm '44 strikes the dog 48 and is raised thereby, thus, through the link 52 and arm ill valve I94 counterclockwise (Figs. 1, 2, -4,' 5 and 6) to a position such that the directional valve I33 will be moved to its coarse feed position shown in Fig. 11.

Under these conditions, the rate at which the head will be moved forwardly will be determined by the rate at which the oil in the rod end of cylinder 29 may escape to the sump through the coarse feed valve feed governor valve I16 and the coarse feed gov+ ernor valve I66.

It will be understood that the rate at which oil will fiow through a restricted passageway or orifice depends upon the differential pressure involved, as well as upon the size of the passageway or orifice. Since the size of the passageway through the coarse feed valve I36 does not vary after it has been adjusted to the desired position, it is necessary to maintain uniformly the differential pressure upon opposite sides of this orifice or pasageway, and this isv accomplished with avery high degree of accuracy by the feed governor valve I16, since any slight increase in pressure in the chamber I94 of the feed governor valve results in upward movement of the valve "6 and consequent restriction of the flow of oil into the chamber I94 until the pressure in the latter chamber again drops to the predetermined value.

After the head of the machine tool has thus been controlled for the coarse feed portion of its cycle, the lower end of the arm will engage the dog 41 and swing further counterclockwise. thereby to shift the automatic pilot valve I04, and hence the directional valve I33 to their respective fine feed positions. It will be recalled that when the directional valve I33 is in its fine feed position, the passageway 2I0.3 from the coarse feed control valve I36 is blocked so that the only pathway-for the escape of oil from the rod end of the cylinder 26 is through both the valve 2I2.

Due to the greater restrictions offered to the flow of oil through this path, the amount of the restriction depending principally upon the ad+ justment of the fine feed valve ill, the head of the machine tool will be moved forward at a very slow rate which is predetermined to correspond with the desired feed rate of the tools 3| into the work piece 40.

After the tools have completed their respective operations upon the work piece, the limit switch actuator 66 will engage the limit switch dog 66 and thereby close the limit switch 64a. The closure of this switch'will result in energization of the solenoid I64 which will swingthe automatic pilot valve I04 counter-clockwise to its rapid reverse position, with consequent movement of the directional valve I33 to its rapid reverse traverse position. as shown in Fig. 13.

It will be noted that in order to move from its fine feed position to its rapid reverse traverse position, the directional valve I33 must move through its stop position.

The rapid reverse traverse portion of the operating cycle is arrested by engagement of the downwardly projecting arm 44 with the dog 45,

v the shape of the part of the dog 45 engaged by the end of the arm 44 being such as accurately to locate this arm in a position such that the automatic pilot valve I04 and consequently the directional valve I33 are accurately moved to their respective stop or neutral positions. As a consequence, the head will come to rest and the operator may then remove the work piece from the table 36 and replace it with another piece to be machined.

If during any part of the cycle of operations, a

a tool should break or for any other reason the operator considers it undesirable for the machine to complete its normal cycle of operations, the operator will press the push button 60, thus closing the switch 60a, and initiating a rapid traverse movement of the head, irrespective of the posi- I96 and through the fine feed I conveniently and accurately.

tion of the head at the time (assuming that it is not in its fully retracted stop position) The operation above has been described on the assumption that the handle 56 is in its upper or automatic control position with the hand pilot valve I03 locked in'position by the locking pin.

vover valve I02 from the position in which it is shown in Fig. 7 to the position in which it is shown in Fig. 8. Whenever this is done; the handle 54 is of course in neutral or stop position, because it is always held in this position by the locking pin III, and therefore movement of the head of the machine tool cannot result from merely shifting the handle 56 from automatic control position to hand control position, but if the head is in motion at the time the shift from automatic tohand controlis made, the head will of course come to rest.

After such shift of the handle 56 has been effected, the hand pilot valve I03 assumes control of the position of the directional valve I33 by virtue of the change-over eifected by the throw-over valve I02. As a consequence, the directionalvalve may be moved to any one of its five positions merely desired position. When the throw-over valve handle 56 is in the hand control position, the movement of the arm 44 by the dogs 45, 46 and 41 will not have any effect, nor will the limit switch 64a have any effect upon the movement of the tool head. Thus, the handle 54 may be moved to position to cause any desired movement of the head of the tool. For example, during the setting up of the machine, the handle 64 may be moved to the fine feed position and the head made to move very slowly through any desired distance so that adjustments of the positions of the tools and of the dogs 45, 46, 41 and 66 may be made The fact that the machine tool head will always v,come to rest when the handle 56 is swung from automatic to hand position is an advantageous feature since the handle 56 may be moved in this manner as a convenient method of quickly stop- .ping movement of the head. It will be understood, from the above description, that the hand controlled pilot valve is locked in its neutral or stop position whenever the handle 56 is in automatic control position. Thus, upon shifting this handle from automatic to hand control position, the hand controlled pilot valve immediately causes the directional valve to move to stop position, irrespective of its previous position.

Furthermore, when the hand controlled pilot valve is in use to direct the hydraulic traverse means, the automatic pilot valve is nevertheless moved by the cams or dogs 45, 46, and 41 and the solenoids I64 and I66 so that it is at all times in the positionnecessary to resume control at the proper point in the cycle. This is important in setting up because the operator can, using the hand control, cause the machine head to rapidly travers forwardly past the feed cam oracams and then stop the traverse, reeposition the feed cam or cams, change to automatic control, and the machine head will then resume the automatic cycle in feed traverse.

It should be clearly understood that while the operator is controlling the position of the machine' by swinging the handle 54 to the of the various valves the automatic pilot valve head by the handle 54, I04 is moved by the engagement of the dogs 45. 46, and 41 with lever 44, and by the solenoid IE6 controlled by th limit switch 64a. This movement of the automatic pilot valve I04 depends solely upon the position of the machine tool head with respect to the dogs, However, the automatic pilot valve is ineil'ective until the handle 58 is again shifted to the automatic position.

Upon completion of the days operations, the operator will press the push button 62 which opens switch Bla and stops the motor 28. If desired, such operation of the push button 62 may also be made to ie-energize the circuit which supplies electric power to the solenoids I64 and I66 either directly or through a. suitable relay.

It will be noted that the bores in which the various valves are mounted all extend to the front surface or enact the end surfaces of the panel 9 and that by removal of suitable bushings holding the valves in place and sealing the ends of these bores, the valves may readily be removed for inspection, cleaning, or replacement. Thus, substantially all of the parts of the hydraulic control mechanism are accessible without removing the panel 96 from the housing 25. Furthermore, practically all of the various passageways and ducts by which the various valves are interconnected, are formed by holes drilled in the panel itself, so that very little piping external to the panel is required.

Since the rear face of the panel is directly above the sump within the housing 25, such passageways as lead to the sump (e. g. 2388, 0S and 2268) require no connections. In addition, it will be noted that the passageways connecting the various valves are very short and have very few bends therein, so that they offer relatively little frictional resistance to the rapid flow of the oil between the valves As a result, the operation is extremely rapid.

By virtue of the fact that the pilot valves are provided to control the flow of oil to the ends of the directional valve cylinder, the solenoids used to control the directional valve through the intermediate operation of the automaticipilot valve maybe very small, thus requiring a small amount of "electric power for their energization, and making it possible to attach them in convenient position for direct operation of the automatic pilot valve.

Due to the sequence of the portions of the cycle whereby the directional valve must move through stop position before being moved to reverse position, and can only be moved from reverse position to another position by passing through the stop position, the possibility of jarring the machine head by having the directional valve pass through reverse traverse position as an incident to passing from stop to forward traverse position, is avoided, with resultant elimination of undesirable jarring of the tool carrying head.

While the hydraulic control apparatus of our invention is illustrated as applied to the control of an automatic horizontal drilling machine, it

will be understood that the apparatus may be chine tool which has 9 principles of the invention. We therefore desire by the following claims to include within the scope of our invention all such modified and similar apparatus whereby substantially the results of 1 our invention may be obtained in a similar manner by substantially the'same or equivalent means.

We claim:

1. In a hydraulic control apparatus for a maa hydraulic piston and cylinder for moving a part thereof, the combination of a directional valve for controlling the flow of oil to and from the ends of said cylinder, a pair of pilot valves, each of said valves comprising an actuated element and a follower element, means for moving said. follower elements distances proportional to the distance said directional valve is moved, and hydraulic means for moving said directional valve in response to relative movement of the elements of, one of said pilot valves.

2.-In a hydraulic control apparatus for a maa sleeves, a

der for moving a of valves which are part thereof, the combination of a panel, a pair of bores in said panel, pilot valve follower spectively. pilot valve elements rotatable in said directional valve for controlling the admission of oil under pressure to and the discharge vof oil from said cylinder, valve ports opened and closed by relative movement of said elements and their respective sleeves to control the position of said directional valve, and a mechanical connection between said directional valve and said sleeves to cause said sleeves and directional valve to move proportionately.

3. In a hydraulic control apparatus for a machine tool which has a hydraulic piston and cylinder for moving a part thereof, the combination of a pilot valve having two elements movable with respect to each other and forming a plurality opened and closed by such relative movement, means for mechanically moving one of said elements in response to the position of said machine tool part, a directional valve for controlling the charge of oil from said cylinder, and gearing connecting said directional valve with the other of said elements of said pilot valve.

4. In a hydraulic control apparatus for a ma chine tool which has a hydraulic piston and cylinder for movinga part thereof, the combination of a pair of pilot valves, a directional valve for a controlling the admission to and the discharge of readily adapted for the control of any machine tool part which is to be moved through a reciprocatory cycle at controlled-speeds for differentportions of the cycle.

While, we have shown and described afparticular embodiment of our invention, it will be apparent to those skilled in that art that numerous modifications and variations thereof may be made without departing from the fundamental oil from the ends of said cylinder, hydraulic and mechanical means interconnecting said pilot valves and said directional valve for controlling the position of said directional valve in response to the positions of said pilot valves, and manually operable means for rendering one or the other of said pilot valves ineffective to control the operation of said directional valve.

5. In a hydraulic control apparatus for a machine tool which has a hydraulic piston and cylinder for moving a part thereof, the combination of an automatic pilot valve and a hand pilot valve, means responsive to the position of said machine tool part to control the position of said automatic pilot valve, a handle for manually con trolling the position of said manual pilot valve, a

directional valve responsive to the position of one of said pilot valves for controlling the operation of said hydraulic piston and cylinder, and a throw-over valve for. selectively rendering said sleeves rotatable in said bores re-' admission of oil to and dissaid cylinder, hydraulic means for actuating said valve, said last-named means including a pair of pilot valves and means for selectively rendering either of said pilot valves ineffective to control said main valve.

7. A hydraulic control apparatus comprising a body having a pair of parallel bores therein, pilot valve sleeves in said bores respectively, pilot valves rotatably mounted in said sleeves, a direc-' tional valve cylinder extending in a direction perpendicular to said bores, a directional valve reciprocable in said cylinder, and a driving connection to cause rotation of said pilot valve sleeves upon reciprocation of said directional valve.

8. In a hydraulic control apparatus, the combination of a pair of pilot. valves, a directional valve hydraulically operated under the control of said pilot valves and mechanically connected to partsof said pilot valves for positioning the latter, and a throw-over valve for optionally rendering either of said pilot valves ineffective to control said directional valve.

9. In a hydraulic control apparatus for a machine tool which has a hydraulic piston and cylinder for moving a part thereof, the combination of a directional valve for controlling the'fiow of oil to and from the ends of said cylinder, a pair of pilot valves, each of said valves comprising an actuated element and a follower element, means for moving said follower elements distances proportional to the distance said directional valve is moved, means for selectively rendering one of said pilot valves ineffective, and hydraulic means for moving said directional valve in response to relative movement of the elements of the other of said pilot valves.

10. A pilot valve assembly for fluid control apparatus, comprising, a rotatable sleeve havinga pair of ports therein, a valve element rotatably mounted in said sleeve, said element having two pairs of chambers, the chambers of a pair being on diametrically opposite sides of said element and located so as to communicate with one of said ports upon relative movement of said element and said sleeve, a source of fluid under pressure, a reservoir at substantially atmospheric pressure, passageways connecting two of said chambers on the same side of said element to said source, passageways connecting the other two of said chambers to said reservoir, and a recess formed in said element between said pairs of chambers and connected to said source, said recess being shaped to balance the forcesdue to fluid pressure acting upon said element in said chambers which are connected to said source.

11. In a hydraulic control apparatus for a machine tool which has a hydraulic piston and cylinder for moving a part thereof, the combination of a panel, a pair of bores in said panel, pilot valve follower sleeves rotatable in said bores respectively, pilot valve elements rotatable in said sleeves, a directional valve mounted for movement in said panel for controlling the admission of oil under pressure to and the discharge of oil from said cylinder, valves operated by relative movement of said elements and their respective sleeves to control the position of said directional valve, a pair of racks on said directional valve, a pair of pinions on said sleeves meshing respectively with said racks to cause said sleeves and directional valves to move proportionately.

ROBERT A. SCHAFER. RALPH RODAL. 

